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Chapter 5 Steady electric currents

Chapter 5 Steady electric currents. Conduction currents : Drift motion of conduction electrons of holes in conductor or semicond. Electrolytic currents : Migration of positive or/negative ions. Convection currents : Motion of elections ions in vacuum.

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Chapter 5 Steady electric currents

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  1. Chapter 5 Steady electric currents Conduction currents : Drift motion of conduction electrons of holes in conductor or semicond. Electrolytic currents : Migration of positive or/negative ions. Convection currents : Motion of elections ions in vacuum. Kirchhoff’s voltage law : Electromotive force Kirchhoff’s current law : Conservation of charge Ohm’s law : V=IR

  2. 5-2 Current Density & Ohm’s law (Volume) current density ， 電荷流過 表面為 ：單位體積電荷 ：電荷流動之速度 ：電荷隨時間之改變率 ：free charge per unit volume ：convection current density

  3. Ex：5-1 負數 代回

  4. 求 ,必須解Poisson’s Equation *同乘以 child – langmuir law 積分左式： 右式：

  5. * 多種載子(e、p、ion…) 半導體 (電子與電洞) 金屬導體 [point form] of ohm’s law 電路學 : ohm’s law

  6. Point form ohm’s law Potential Difference of terminals is length cross-section Point form ohm’s law derive 與 結合 Ckt ohm’s law

  7. Ex：5-2 Sol : Conductance (G) b)並聯(電壓一樣) 電路學 a) 串聯(電流一樣)

  8. 5-3 Electromotive Force & Kirchhoff’s voltage Law static electric field Electromotive force V ohm’s law Inside source outside inside The source of the nonconservative field Electric battery,……. outside Impressed electric field intensity

  9. Ohm’s Law Charge cumulation Chemical action 推廣 k個 R Kirchhoff’s voltage Law

  10. 5-4 Equation of Continuity and Kirchhoff’s Current Law • Principle of conservation of charge Current leaving the region = total outward flux of Divergence Theorem equation of continuity

  11. Steady currents, , Kirchhoff’s current Law Conductor 內 其中 ：relaxation time

  12. 5-5 Power Dissipation & Joule’s Low 單一原子 work Power drift velocity Total power : point function Power density under steady-current Joule’s Law

  13. A constant cross-section ds dl

  14. 5-6 Boundary conditions for current density Steady current Differential Integral

  15. Ex：5-3

  16. Steady current flows 2 lossy dielectrics 1 2

  17. Ex 5-4 : static charge & steady current 同時存在 Interface surface charge surface charge upper lower

  18. 5-7 Resistance Calculations capacitance ohm’s Law resistance

  19. Ex：5-5

  20. 計算電阻R的步驟 1. 針對問題 , 選擇適當座標系統。 2.假設兩導體之電位差V。 3.求出兩導體間的電場 。 4.求總電流 5.

  21. Ex：5-6 Cylindrical coordinate Laplace’s equ Find total current 代入

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